Formation of spherical particles or bodies from ceramic materials, particularly from oxides, is well known. The particles formed may be as small as sub-micron, or may be as large as a millimeter, in diameter.
For example, spheres up to several hundred microns in diameter were produced by a sol-gel approach during development of nuclear fuel rods. At the other end of the scale, various techniques, including sol-gel techniques, are described for producing very small spherical particles on the order of a micron up to tens of microns in diameter. These techniques are described in the technical literature, and particularly patent literature. Examples are found in the following United States patents: U.S. Pat. No. 4,940,477 (Bocko et al.), U.S. Pat. No. 5,108,665 (Crooker et al.) and U.S. Pat. No. 5,108,674 (Stebbins et al.).
Characteristically, the spherical particles were produced with a wide, and often uncontrolled, range of particle sizes. My U.S. Pat. No. 4,871,489 describes a method and apparatus for producing spherical particles having a narrow size distribution. In accordance with that patent teaching, droplets are formed by forcing a thin, liquid stream of a sol through an orifice under pressure, and applying a periodic vibration to break up the stream. This is referred to as the vibrating orifice, or the Rayleigh instability, method. The droplets formed in this manner have a narrow size distribution. They may be dried to form spheres which may be in the 1-10 micron size range, although not so limited.
Spheres formed in this manner find various applications as disclosed in the patent. In addition, for some purposes, it is desirable to have bodies in other non-spherical forms. In particular, cylindrical rods, or barrel-shaped particles, may be required for such purposes as light focusing.
Accordingly, a primary purpose of the present invention is to supply such alternative, non-spherical shapes.
Another purpose is to provide a convenient method of reshaping spherical particles into such other non-spherical shapes.